He says emergency services were on the scene quickly.
It comes just a week after another Wellington bus driver had a medical event which resulted in him driving the wrong way down a busy motorway at speed.
Metlink's general manager Scott Gallacher told the Herald the bus was intercepted by police after travelling the wrong way along Centennial Highway.
"Thankfully, and this is the most important thing, no one was hurt and we understand there was no damage to either the bus or any other vehicle. An ambulance was however called to the scene and the driver is receiving medical attention. The bus was not in service, and there were no passengers."